In a rectangular container 20 decimeters long and 15 decimeters wide, there is water 20 decimeters deep. Now a cube iron block is sunk in the water, and the water surface rises 09 decimeters. What's the volume of this cube iron? 2. There are three cube iron blocks, their surface areas are 24 square centimeters, 54 square centimeters and 294 square centimeters respectively. Now dissolve the three iron blocks into a big cube, and find the area of the big cube

one
Volume = 20 × 15 × 0.09 = 27 cubic decimeter
two
The side lengths of the three cubes are 2, 3 and 7 cm respectively
Their volumes are 8, 27, 343 cubic centimeters
Total volume = 8 + 27 + 343 = 378 CC
Is it total volume or total area?
Total area = 6 * 378 ^ (2 / 3) cm2
If the explanation is not clear enough,

In a cuboid container with a length of 20 decimeters and a width of 15 decimeters, there is water 20 decimeters deep. Now a cube iron block with an edge length of 30 cm is sunk in the water. How deep is the water in the container?

20+3^3/（20*15）=20.09
2.009m

The definite integral of the absolute value of (COS x) between 0 and Pai

∫[0,π]|cosx|dx
=∫[0,π/2]cosxdx+∫[π/2,π](-cosx)dx
=sinx|[0,π/2]-sinx|[π/2,π]
=1-(0-1)=2

10 is the product of which two identical numbers are multiplied

x²=10
X = ± root 10

Formula for calculating cylinder volume

π R & # 178; H (π × square of radius × height)

0, 1, 2 and 3 constitute natural numbers without repeated numbers. Arrange these natural numbers from small to large, and 1230 is the number number number of the sequence

First of all, the current books all say that the minimum natural number should be 0, and we should also pay attention to that when there are multiple numbers, 0 can not be in the first place. To form a single digit: there are 0, 1, 2, 3, a total of 4 (pieces) to form two digits: there are A31 methods to determine ten digits first, and then there are A31 methods, so there are A31 × A31 = 9 (pieces)

It is known that the solution set of inequality x + 8 > 4x + (M is a constant) is X

Transfer: 8-m > 3x
x

It is known that a hot-air balloon moves into the air. It is known that the temperature drops by 6 ℃ for every 1000m rise in height. Now the measured ground temperature is 6 ℃, and the temperature at the height of the balloon is - 3 ℃. Calculate the height of the balloon
The formula is also added.

6 - (- 3) = 9 ℃ 9 △ 6x1000 = 1500 ℃

What are the definitions and properties of the center and gravity center of a triangle?

A triangle has only five hearts
Center of gravity: the intersection of the three middle lines;
Perpendicularity: the intersection of three heights;
Heart: the intersection of the bisectors of the three interior angles is the abbreviation of the center of the inscribed circle of the triangle;
Outer center: the intersection of three vertical lines;
Side center: the intersection of an inner bisector and other two outer bisectors. (there are three). It is short for the center of the side tangent circle of a triangle
If and only if a triangle is an equilateral triangle, the center of an equilateral triangle is the four centers

If f (x) = a ^ X / (a ^ x) + 1 (a > 0, a is not equal to 1)
Then the range of the function g (x) = +

If f (x) = a ^ X / (a ^ x + 1) > 0, then f (x) + F (- x) = a ^ X / (a ^ x + 1) + 1 / (a ^ x + 1) = 1;
From the meaning of the title: F (x) - 1 / 2 ≤ {< f (x) - 1 / 2}